Telecommunications equipment is crucial to the data networks relied upon by modern society. The data networks include any type of network for the transport of data, without regard to the format of the data or the method of transport. The telecommunications equipment includes network interconnections and devices for fiber optic networks, copper-based networks, and other telecommunication technologies as they may be developed in the future. The networks require interconnection points and equipment for the operation of the networks at various locations. Many of these interconnections and equipment locations are distributed and are not located inside buildings. As a result, enclosures to protect the equipment from the outdoor environment are a necessary component of such networks.
One example of such an enclosure is an enclosure for an outdoor distribution hub for a fiber optic network. Outdoor Fiber Distribution Hub (FDH) products serve as a passive interface between the telecommunication provider's feeder network and their individual distribution cables serving their customers. FDHs are sometimes referred to as fiber hubs or service access terminals, and they perform a similar function as the traditional telephone network Serving Area Closure (SAC) does for copper networks. The FDH is exemplary of the type of the below grade enclosures described herein, but is not limiting as to the use or design of such enclosures.
The principle function of an FDH is to provide mechanical and environmental protection for fiber optic components in an enclosure that permits fiber optic communications service to be divided among customers, broadcast fashion. In some embodiments, an FDH also provides a management system for optical splitters, fiber, and connectors providing considerable flexibility to the optical plant network. This enables the local feeder/distribution/loop network to be configured to cost-effectively meet the needs of both the service provider and their customer. In addition, the FDH serves as a convenient test access point to verify the integrity of the service provider network and the customer equipment.
Depending on the specific needs of the service provider, the feeder cable side of the FDH often will be used to terminate Outside Plant (OSP) fiber optic cables to smaller size distribution fiber cable to serve individual customers. Since the FDHs store cable splices and optical connector cross-connects, they must be capable of resisting damage from the outside plant environment they will occupy. In some cases, the FDHs may be located below grade, on a pad as a ground-mounted closure, or on a pole as a pole-mounted closure. The FDH is usually secured with a lock that prevents access by the public or other non-service provider personnel. The FDH is not intended to provide access for customers, either residential or business.
Optical feeder cable enters the closure (often from the rear or bottom of the closure) and is spliced to optical fiber in the FDH's splice panel. Output fiber pigtails or jumpers from the splitter module are used as optical pathways between the optical signal provided by the service provider in the feeder cable to optical pathways to the customer receiving this service as optical cross-connects. The splitter output fibers are terminated on the optical distribution panel, which provides a direct pathway to the local customer for the service. Each fiber from the distribution cable to the customer is terminated on the rear side of the optical cross-connect panel. All routing pathways within the FDH meet general acceptable fiber and cable handling and geometry requirements used in the industry. In addition, the FDH is equipped with a parking area to store optical fibers not in use prior to deployment as cross connects on the fiber cross-connect panel being used as optical input to a 1×N optical splitter module.
In other embodiments, the enclosures described herein may provide environmental protection for components of copper networks, coaxial networks, electrical conduit, low voltage electronic systems, or any other interconnections or equipment that require a environmental protection. The equipment installed in the enclosure may include any type of equipment necessary for the operation of the network.
In some embodiments, the below grade enclosure includes a lift assist system to allow a network technician to raise the enclosure to above ground level for more convenient access to the interior of the enclosure.
FDHs and other similar enclosures are most commonly located in OSP uncontrolled environments. It is possible, however, that these closures could be used inside a building in a controlled environment.
Until recently, optical connectors were traditionally found in the service provider's Central Office (CO) (head end) or in remote locations that are environmentally controlled, such as Cable Entrance Vaults (CEVs) or Remote Terminals (RTs). More recently, as broadband fiber architectures have penetrated the local distribution loop, connectors are increasingly found in optical nodes (Hybrid Fiber Coax [HFC] networks) and optical network units (FTTC networks). The enclosures for these network elements, although typically not hermetically sealed, do provide robust mechanical and environmental protection for the optoelectronic equipment. In addition, the heat dissipated from the electronics is often sufficient to maintain a relatively dry environment.
FDHs, however, contain only passive optical components. In keeping with the need for easy craft access in an OSP environment, both for the service provider and the customer, it is desirable to avoid hermetically sealing the FDH. Therefore, the optical connectors and possible optical components will be subjected to the harsh OSP environment. Similarly, enclosures for networks of other types may also need to provide environmental protection to active or passive network components or interconnections.
The enclosures for such networks, such as for outdoor FDHs, may be deployed in a variety of locations. A brief description of each deployment environment is provided below.
In some deployments, the enclosures are deployed in a protected environment such as a Cable Entrance Vault (CEV), telecommunications closet, computer room, or similar location. The enclosure need provide only minimal environmental protection (dust and water spray resistance are applicable).
In other deployments, an enclosure designed for attachment to a building exterior may be utilized. In such deployments, full frontal access is generally required. The enclosure may be required to be flood proof in some applications.
In ground level outdoor deployments, primary mechanical and environmental protection comes from the outer enclosure (e.g., pedestal and cabinet), which may contain smaller sub-enclosures dedicated to the needs of the service provider and the customer. These may be either flood-proof or rain-resistant.
In other deployments, the enclosures are installed on an aerial pole or stand. In this environment, free-breathing enclosures are acceptable provided they use fiber, cable, and fusion splices meeting current Telcordia environmental requirements.
In other deployments, the enclosures are installed below grade in conjunction with a handhole or similar installation.
The enclosure described and claimed herein may be used in various embodiments in any of the deployment types. In some embodiments, the enclosures have specific features to provide improved performance over other enclosures in a below grade deployment.